An electrophotographic light-sensitive member consists essentially of a photoconductive layer formed on an electroconductive support. The photoconductive layer consists of, for example, amorphous selenium or zinc oxide-resin coatings, and the electroconductive support consists of, for example, a metal plate or a metal-coated resin film.
In one of the electrophotographic processes, the following steps (1) to (5) are usually involved:
(1) Sensitizing the photoconductive layer by a corona discharge.
(2) Exposing the photoconductive layer to form an electrostatic latent image.
(3) Developing the latent image with charged fine particles, i.e. toners.
(4) Transferring the developed image to other material such as paper, and
(5) Fixing the image to the paper by fusing or by virtue of the self-fixing quality of the toner.
In the electrophotographic process, some of the toner usually remains on the photoconductive layer after the transferring of the developed toner image. The remaining toner should be removed to carry out the next process. The removal of the remaining toner, i.e. the cleaning of the photoconductive layer, is performed by "brushing". The photoconductive layer receives scratches on the surface by the developing, transferring and cleaning steps. The scratches increase by repeating the process. These scratches have a bad effect on the formation of the toner image, and therefore a vivid copy cannot be obtained.
In order to obviate the defects as stated above, there has been proposed the formation of a protective coating on a photoconductive layer. As material of the protective coating, the following high polymers are conventionally employed: polystyrene, poly-n-butyl methacrylate, polyamide, polyester, polyurethane, polycarbonate, polyvinylformal, polyvinyl acetal, polyvinyl butyral, ethyl cellulose, nitrocellulose and acetylcellulose.
In order to protect the photoconductive layer and increase the durability of the light-sensitive member, a thick protective coating is required. However, the thick protective coating gives low resolution. The resolution is expressed as the number of lines per millimeter (lines/mm). Amorphous selenium can give a resolution of 7 to 9 lines/mm. However, amorphous selenium having a protective coating of the organic high polymer as shown above gives various resolutions dependent on the thickness of the coating as follows:
______________________________________ Thickness of protective coating Resolution ______________________________________ 0.5.mu. 5-8 lines/mm 1.mu. 4-6 lines/mm 2.mu. 3-5 lines/mm ______________________________________
It is understood that the resolution depends on the kind of organic high polymer employed. As can be seen in the above, high resolution usually can be obtained if the protective coating is less than 0.5.mu. in thickness. When such a thin protective coating is used, however, high durability cannot be obtained, namely, the number of the printed copies which can be obtained is less than twenty thousand.
It is an object of the present invention to provide electrophotographic light-sensitive members which have high durability and resolution.